1. Technical Field of the Invention
The present invention relates to SAW oscillators, and more particularly, to a SAW oscillator including at least a semiconductor integrated circuit, a SAW device, and a passive component in a package.
2. Background Art
Due to the recent progress in semiconductor technologies, an oscillator including an oscillation circuit within a package is becoming smaller and highly integrated.
There is a demand for oscillators with higher oscillation frequencies and measures against high loads.
However, when wiring or a wiring pattern forming an oscillation loop becomes longer, the parasitic capacitance (stray capacitance) or the parasitic inductance in the high frequency range (for example, 100 MHz or higher) becomes increased. If the parasitic capacitance is increased in the oscillation loop, the dielectric loss becomes larger and the load impedance is increased in the high frequency range. Accordingly, the gain is decreased, and as a result, a desired oscillation frequency cannot be obtained or oscillation itself cannot be obtained in the oscillation circuit.
If the parasitic inductance is increased (added) in the oscillation loop, the load impedance is increased in the high frequency range. Accordingly, the gain is decreased, and as a result, a desired oscillation frequency cannot be obtained or oscillation itself cannot be obtained in the oscillation circuit.
In view of this background, Japanese Utility Model Registration Application Publication No. 5-70015 discloses that the length of wiring in the oscillation loop, and in particular the output side wiring, may be decreased. The oscillator disclosed in Japanese Utility Model Registration Application Publication No. 5-70015 uses a quartz resonator, and a semiconductor integrated circuit (IC) connected to the quartz resonator is disposed toward the output side so that the length of the wiring for the semiconductor integrated circuit at the output side is decreased.
In the invention disclosed in Japanese Utility Model Registration Application Publication No. 5-70015, the parasitic inductance or the load impedance occurring at the output side wiring can be prevented. However, the total length of the wiring or wiring pattern is not changed in the entire oscillation loop. Accordingly, increased load impedance cannot be prevented in the entire oscillation loop.
Accordingly, to solve the above-described problem, it is an object of the present invention to provide a SAW oscillator that can prevent an increased parasitic capacitance or an increased parasitic inductance even in the high frequency range by minimizing the length of the wiring or wiring pattern in the entire oscillation loop.